In the prior related patents and copending application referred to above there has been described a spectrophotometric method and apparatus directed to non-invasive, continuous, atraumatic, in vivo, in situ monitoring of metabolism in a body organ. In the described method and apparatus, measuring and reference wavelengths within the near-infrared region, i.e., 700-1300 nm, are utilized with light source and light detector devices mounted on the body for non-invasive, continuous, atraumatic, in vivo, in situ monitoring of oxidative metabolism by monitoring oxygen sufficiency in an internal organ, e.g., the brain, of a human or animal body. Advantage is taken of the critical characteristic of cellular enzyme cytochrome a, a.sub.3 (also known as cytochrome c oxidase and identified by EC 1.9.3.1) within the optical path and within the radiated portion of the selected organ for absorbing the selected measuring wavelength and for light of this measuring wavelength, as well as at least one reference wavelength within the same defined infrared region and at a low, non-hazardous level of intensity to be detectable at the end of a relatively long transillumination or reflectance path, e.g., of several centimeters length, which may include substantial content of bone as well as soft tissue and skin. Variations in metabolic and circulatory parameters during measuring are recognized and the selection of wavelengths, circuitry and method also provide techniques for compensating for changes in blood volume in the organ being monitored, for continuous monitoring of hemoglobin oxygenation and blood volume, for intermittent monitoring of blood flow rate, for skin blood flow effects and variations in the light source, e.g., laser diode, output.
A useful background of the prior art may be had by making reference to the discussion of the prior art in the mentioned related prior patents and to the light source and light detecting structures described in U.S. Pat. Nos. 3,527,932; 3,674,008; 3,638,640; 3,704,706; and 4,077,399.
In the context of the mentioned related prior patents and copending application and related prior art, the present invention is primarily concerned with the means for mounting the light source-light detecting devices on the body, particularly on the head for brain monitoring. Thus, the present invention is primarily intended to provide an improvement over the light source-light detecting structure shown in the prior patents and in copending application Ser. No. 289,413 as well as over all known prior art deemed relevant to the invention.
Taking all of the foregoing into account, further development and experimentation with the spectrophotometric apparatus and method of the prior related patents and particularly with the strap structure for mounting the light source-light detecting devices on the body as set forth in copending application Ser. No. 289,413, has revealed a need for an even further improved means for securing, spacing and shielding the light source as well as the light detector when mounted on the body and such that a strap is not required. This needed improvement is of particular significance in those medical and surgical procedures in which the patient is prone and the head of the patient is required to be tilted back, either for examining or introducing substances or instruments into the throat of the patient. In addition to providing a light source-detector mounting arrangement which does not require use of a strap for attachment and securement, there is a continuing need for the mounting structure in whatever form it is made to be reproducible in a low cost form and where necessary in a form lending itself to a single end use application for at least the most inexpensive components of the mounting structure so as to minimize sterilizing procedures for those components of the mounting structure not suited to a single end use.
The achievement of these various needed and other improvements thus becomes the object of the invention and other objects will be revealed as the description proceeds.